The Foundation layer in the OutSystems Architecture Canvas is designed to contain the most generic and reusable components. These modules serve as the fundamental building blocks for the entire application portfolio, providing non-functional requirements or integrations with external systems (e.g., SAP, Salesforce). By abstracting these core functionalities into a separate, stable layer, they can be consumed by numerous Core and End-User applications, thus achieving the highest rate of reusability, promoting consistency, and simplifying maintenance across the factory.

A. The End-User layer contains application-specific UI, screens, and business processes. It is the least reusable layer by design, as it serves a single application's entry point.

B. The Core layer offers reusable business-agnostic services and concepts. While it promotes reusability, it is less generic than the Foundation layer, upon which it depends.

1. OutSystems Official Documentation

"Designing the architecture of your OutSystems applications

" Section: The 3 Layers of the Architecture Canvas. It states

"Foundation modules are libraries that provide reusable

non-functional and functional assets to be used across multiple applications... They provide a solid and generic foundation for all your applications

promoting a high level of abstraction and reusability."

2. OutSystems Official Documentation

"Architecture Canvas

" Section: Foundation Layer. This section details that Foundation modules "implement the integrations with external systems or define widely used data models with the entities that are shared among many applications." This shared nature is the basis for its high reusability.

3. OutSystems Official Documentation

"Architecture Dashboard

" Section: Code patterns detected by Architecture Dashboard

Pattern: Incorrect Abstraction. The documentation explains that placing reusable logic in higher layers (like End-User) is an architectural flaw

reinforcing that reusability is a primary characteristic of the lower layers

especially Foundation.